Hurry! Metal roof coatings HELP

[gotrocks]

Hello to All,
My old barn/shop metal roof is getting more rust at time marches on.
It has not rusted through, and is still pretty sound but ?for how long?

Please give me your thoughts on which coating material to consider.

EPDM, poly, liquid rubber, etc.

Thank you. Norris

 

[JB4310]

If it can still be coated, ie no perforations the one of the best materials would be aluminum roof coating, we use it all the time, not the Home depot brand but a good brand like Bull Dog or Karnack, about $75. a 5 gal pail, mop it on with a 3-4 knot brush.
Good luck,

 

[QRTRHRS]

Reminds me of a project years ago. A friend had picked up a 50x100 steel barn for cheap and re-erected it on his property. The roof tin had a lot of surface rust so he enlisted a bunch of friends to wire brush it and coat it with the aluminum coating.

It was not a fun job at all. Having moved on and lost contact, I have no idea how long the coating held up. I would think that the rust would remain active even with the coating and continue to deteriorate the metal.

I dunno', would it be more cost effective long term to go with new tin?

 

[LBrown59]

If it can still be coated, ie no perforations the one of the best materials would be aluminum roof coating, we use it all the time, not the Home depot brand but a good brand like Bull Dog or Karnack, about $75. a 5 gal pail, mop it on with a 3-4 knot brush.
Good luck,

They use an alm. coating on mobile home roofs called Kool Seal.

 

[Bird]

They use an alm. coating on mobile home roofs called Kool Seal.

Yep, I've had more experience than I wanted with Kool Seal, but it's primarily for sealing seams and cracks, not for a complete coating (unless there's been some major changes in recent years). And while I don't remember the name of the stuff, there are much better products on the market than Kool Seal.

 

[Erik_in_Hoyt]

start with "rust converter" as your primer, then paint with whatever you want.

 

[KB9UDE]

If it can still be coated, ie no perforations the one of the best materials would be aluminum roof coating, we use it all the time, not the Home depot brand but a good brand like Bull Dog or Karnack, about $75. a 5 gal pail, mop it on with a 3-4 knot brush.
Good luck,

JB-

Will this Bull Dog coating seal the metal roof where nails are fastening it down on my pole barn?? It was constucted several years ago and the rubber washers are all but gone and it is showing small rust areas. Would this product be ideal for coating the whole roof or is there a better product??

John

 

[chh]

I used a cheap silver colored Walmart(if I remember correctly) fibered mobil home roof coating on an old building several years ago. The coating worked OK, but the building got pretty rough after a windstorm a couple of years ago. I dozed out a big hole last spring a pushed the building off in it and burned it. That roof coating and the old masonite siding burned like they were made of diesel fuel. You might want to check the flamibilty of anything you get.

 

[kthompson]

Check with a professional paint store. There are much better materials then Kool Seal. There is at least one that give a white flexible coating.

 

[gotrocks]

Many thanks to all of you. I'll let you know what we decide.....after we decide.
My oldest son had a poster in his room years ago the said;

"Not to decide, is to decide"

 

[JB4310]

JB-

Will this Bull Dog coating seal the metal roof where nails are fastening it down on my pole barn?? It was constucted several years ago and the rubber washers are all but gone and it is showing small rust areas. Would this product be ideal for coating the whole roof or is there a better product??

John

It's not going to fill holes per say, you'd want to seal any holes or open seams with heavy body roof cement and fiberglass membrane first then it would be ideal for coating the whole roof.
The alum coating is a premium oil based product, when you start mixing it you will see the aluminum "solid particles" come up from the bottom, the higher quality stuff has more aluminum. some cheap stuff is more like just paint, the aluminum helps reflect the sun which is the greatest threat to any roof surface, the oil base helps preserve the metal and resaturate asphalt based surfaces.

Will need redoing every 5 years or so, whatever you choose, do something don't let that metal roof go away on you, I hate to see a metal roof neglected when a little coating would go a long way at preserving it.
I thought you'd get more response from agri type experience, my roof experience comes from commercial/ institutional, some residential.

 

[KB9UDE]

Thanks for the info JB

 

[LBrown59]

Many thanks to all of you. I'll let you know what we decide.....after we decide.
My oldest son had a poster in his room years ago what said;

"Not to decide, is to decide"

I haven't decided what to decide so i i haven't decided what i decided.

 

[JB4310]

Thanks for the info JB

After rereading your question if you only have "small rust areas" showing, I'm assuming you have a galvanized metal, no prob using aluminum coating on galvanized, but if it's only small areas around the fasteners then maybe you just need to seal those fasteners and touch up the other small areas of rust with a spray on galvanized coating which is also a premium product just for that application.
Might not need to coat the entire roof at this time.

I'm not up on those exposed fastener type applications so I'm not sure but maybe it would be worth it to replace the screws with new sealing washers?

 

[PILOON]

What has worked great for me to patch little holes is FLEXTRA caulking in tubes.
It sticks extreemly well and is easy to apply with a caulk gun.
Being some sort of poylurathane base it is very weather resistant and accepts paint/stain as well.

They sell it in about 48 colors so color matching is easy.

You can also do big patches if you cut (from the same stock) and match ribbing by running a bead of caulk around the edges before applying and then sheet metal screws every 3" or so, tighten 'til the caulk squeeses out and you have a permanant patch!

I challange you to peel off a patch that was applied in this fashion!

 

[ronjhall]

My barn was built in the early 50's. When I moved here in the 70's it had some signs of rust. Coated with Aluminum Fiber Roof Coating. It has been done 2 more times since then. Last time a year ago. Seems to need it about every 15 years. Got it from HD. I think it was about $30 for 5 gallon.
Wear old cloths, boots and gloves. Plan on throwing them away after putting on roof. Your climate may require a different coating.<br>

 

[rmlucasco]

Asphalt based aluminum coatings do little for a rusting metal roof and absolutely nothing for leaks and will often cause them to develop. They are simple products developed in the 1940s that did an adequate job on the heavier gauge corrugated metal roofs available at the time. They are good UV shields for modified and asphalt but that's it. They are made from an asphalt base, leafing aluminum pigments, a dessicant and cellulose (paper) fibers. More modern (1970s) metal panels are much lighter and more flexible. The fibered aluminum coating will eventually crack and trapped moisture will cause rust to grow underneath, gradually delaminating the coating and causing the rust to develop even faster. Worse, if there are loose fasteners, and there always are, the coating will crack sooner at those points because of fastener movement and cause the panel to rust out at the point of attachment.

Better to locate a modern metal roof restoration system. The most common is water-based acrylic (there are many quality levels) which requires a seam sealer, primer and two coats of acrylic. Water-based is permeable so in northern climates it will rust through eventually unless the primer is an oil based alkyd. Karnak and Palmer offer these but sell a water based primer which is inferior.

Better is a solvent based elastomeric coating like this one: http://rmlucas.com/TPS5000Mailer.pdf if there is already aluminum coating on the roof you'd need to use this one: http://rmlucas.com/6000.pdf
Stronger and more elastic than acrylic with near zero permeability. Seal seams & fasteners then 2 coats. It prevents moisture and oxygen from reaching the roof surface so there can be no rust reaction. You can use a phosphoric acid type rust converter if you wish for added protection.

Karnak has similar to the first but they don't have the second. It will turn yellow or brown if applied to asphalt or aluminum coating. Palmer Asphalt (Bulldog) doesn't. Kool Seal and the like for the trailer market is garbage.

If you want cheap use an alkyd metal primer (like rustoleum) the use the non-fibered aluminum coating. It goes on thin and doesn't last as long but it also doesn't delaminate in "plates" that trap moisture and kill you roof. If you go this waay Karnak or Palmer are fine.

I should disclose that (if you haven't noticed my screen name) R.M. Lucas Co. is my Company. Feel free to contact me with any questions.